Brushless DC motors have the problem of high torque ripple in direct torque control system because of the non-sinusoidal back EMF and two-phase conduction mode. Aiming at reducing the torque ripple in DTC system of BLDCM,the paper proposes an optimized voltage vector selection table. The commutation torque ripple of the different new zero voltage vectors are analyzed and compared by formula deduction. The result shows the commutation torque ripple is effectively suppressed through the combination between upper and lower zero voltage vectors. The simulation and experiment verifies the theoretical analysis.